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1.
gamma-Glutamyl transpeptidase, which is composed of two unequal subunits, exhibits proteinase activity when treated with agents such as urea and sodium dodecyl sulfate. The heavy subunit is preferentially and rapidly degraded. The enzyme also degraded bovine serum albumin in the presence of urea; however, several other proteins and model proteinase substrates were not cleaved. Treatment of the enzyme with 6-diazo-5-oxo-L-norleucine, a gamma-glutamyl analog, results in parallel loss of transpeptidase and proteinase activities indicating that the site at which gamma-glutamylation of the enzyme occurs (presumably a hydroxyl group on the light subunit) is also involved in proteinase activity. The purified light subunit, but not the heavy subunit, exhibits proteinase activity even in the absence of urea. Results suggest that dissociation of the enzyme unmasks the proteinase activity of the light subunit involving the site at which gamma-glutamylation of the enzyme occurs, and that the heavy subunit may impose transpeptidase reaction specificity by contributing the binding domains for gamma-glutamyl substrates.  相似文献   
2.

Background  

Pseudorabies virus (PRV) is an alphaherpesviruses whose native host is pig. PRV infection mainly causes signs of central nervous system disorder in young pigs, and respiratory system diseases in the adult.  相似文献   
3.

Background  

Microarray-based pooled DNA experiments that combine the merits of DNA pooling and gene chip technology constitute a pivotal advance in biotechnology. This new technique uses pooled DNA, thereby reducing costs associated with the typing of DNA from numerous individuals. Moreover, use of an oligonucleotide gene chip reduces costs related to processing various DNA segments (e.g., primers, reagents). Thus, the technique provides an overall cost-effective solution for large-scale genomic/genetic research. However, few publicly shared tools are available to systematically analyze the rapidly accumulating volume of whole-genome pooled DNA data.  相似文献   
4.
Nucleotide sequencing of a rat carboxypeptidase B (CPB) cDNA and direct sequencing of the CPB mRNA via primer extension on pancreatic polyadenylated RNA has yielded the complete amino acid sequence of rat CPB. The rat enzyme is synthesized as a precursor species containing a large amino-terminal fragment (108 amino acids) that contributes a putative signal sequence and an activation peptide. The mature form of rat CPB is homologous to bovine CPB (77% identity); the amino acids in bovine CPB which have been previously implicated in catalysis or ligand binding are invariant in the rat orthologue. The rat CPB cDNA was used as a probe for the isolation of the rat CPB gene. Detailed characterization of three overlapping rat genomic clones demonstrated that the coding region for the rat CPB precursor is sequestered in 11 exons which are dispersed throughout 34 kilobase pairs of genomic DNA. The nucleotide sequence of a large part of the gene has been determined including that of the exons, the exon/intron boundaries, and the 5' flanking region. We also report the partial nucleotide sequence of the rat CPA1 gene. Comparative analysis of the structural organization of the rat CPB, rat CPA1, and rat CPA2 genes (Gardell, S. J., Craik, C. S., Clauser, E., Goldsmith, E. J., Stewart, C.-B., Graf, M., and Rutter, W. J. (1988) J. Biol. Chem. 263, 17828-17836) reveals that, with one exception, the number, position, and sequence composition of the exons in these three carboxypeptidase genes are conserved in spite of considerable divergence with respect to the lengths of their corresponding intervening sequences. Conserved sequences in the 5' flanking regions of the rat CPA1, CPA2, CPB, and other pancreas-specific genes have been identified.  相似文献   
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Gold salts and phenylbutazone selectively inhibit the synthesis of PGF and PGE2 respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE2 and PGF syntheses equally. It is postulated that selective inhibitors may have a different mode of action and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function.  相似文献   
8.
In a variety of tumour systems, individuals carrying progressively growing neoplasms have lymphoid cells with a specific cytotoxic effect on cultured tumour cells from the same individual1–4. Since the sera of tumour-bearing individuals have been shown to prevent tumour cell destruction by immune lymphocytes in vitro2,5–8 and since this serum blocking activity appears early in primary and transplant tumour development5,7, it has been suggested that the appearance of this serum blocking activity might be responsible for the progressive growth of tumours in individuals having cytotoxic lymphocytes. Counteraction of this blocking activity would thus be of primary importance in facilitating the function of an already existing or bolstered cell-mediated immunity. The serum blocking activity might be inhibited in various ways, by preventing the formation of blocking antibody or by interfering with its action (“unblocking”), as demonstrated in Moloney sarcoma regressor sera9. This type of serum also has a therapeutic effect on Moloney sarcomas in vivo10,11, which has been tentatively attributed to its unblocking activity8,9 or, possibly, to a complement-dependent cytotoxicity10. Tumour growth in the Moloney sarcoma system, however, might be due in part to continuous recruitment of neoplastic cells by virus-induced transformation and so the therapeutic effect could be due to a virus-neutralizing serum activity9,10.  相似文献   
9.
In this study, we have demonstrated that the critical hydrogen bonding motif of the established 3-aminopyrazinone thrombin inhibitors can be effectively mimicked by a 2-aminopyridine N-oxide. As this peptidomimetic core is more resistant toward oxidative metabolism, it also overcomes the metabolic liability associated with the pyrazinones. An optimization study of the P(1) benzylamide delivered the potent thrombin inhibitor 21 (K(i) = 3.2 nM, 2xaPTT = 360 nM), which exhibited good plasma levels and half-life after oral dosing in the dog (C(max) = 2.6 microM, t(1/2) = 4.5 h).  相似文献   
10.
The two lysophospholipids (LPs) lysophosphatidic acid and sphingosine 1-phosphate (S1P) regulate diverse biological processes. Over the past decade, it has become clear that medically relevant LP activities are mediated by specific G protein-coupled receptors, implicating them in the etiology of a growing number of disorders. A new class of LP agonists shows promise for drug therapy: the experimental drug FTY720 is phosphorylated in vivo to produce a potent S1P receptor agonist (FTY720-P) and is currently in Phase III clinical trials for kidney transplantation and Phase II for multiple sclerosis. Recent genetic and pharmacological studies on LP signaling in animal disease models have identified new areas in which interventions in LP signaling might provide novel therapeutic approaches for the treatment of human diseases.  相似文献   
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